Copying lathe



H. A. SCHULTZ COPYING LATHE Aug. 9,1927. i,638,511

Filed Nov. .30. 1925 Patented Aug. 9, 1927.

UNITED STATES 1,638,511 PATENT orrica.

HERMAN A. SCHULTZ, OF CHICAGQTLLINOIS, ASSIGNOE TO CHARLES E; REED.

COPYING- LATHE.

App11fcation filed November 30,1925. Serial No. 72,220.

My invention relates, more particularly, to lathes provided for the manufacture of shoe lasts, and more especially graded shoe lasts, and of the type comprising, as an element, a swing-frame which, in lathes of this type as commonly provided, has revolubly mounted thereon the pattern and the work, to cooperate with a pattern follower and the cutter, respectively.

In the turning of irregular objects, as for example and more particularly some forms of shoe lasts, by machines, as heretofore provided, the machines are required to be op erated relatively slowly, to produce work of the same shape as the pattern, where the pattern presents surfaces, as is common in some forms of shoe lasts, extending at a relatively small acute angle to each other. The requirement for such slow operation is due to the fact that the pattern in moving against the follower at the portions referred to has a tendency not to hug the follower in the initial movement of the frame toward vertical position. g

The object of my presentinvention is to provide improvements in copying lathes of the type referred to, whereby thespeed of the machine may be materially increased as compared with the speed at which machines as hitherto provided are required to be 0perated, and produce work of the same sharp contour as the pattern and by mechanism which shall be of simple and economical construction and not be liable to become impaired in use. I

lVhile my improvements are applicable to quite a wide range of types of machines, I have chosen to illustrate them in a machine of the type shown in the pending application of Charles-E. Reed for U. S. patenton lathes, Serial No. 650,194, filed July 7, 1923, wherein the swing frame referred to is pivotally supported at its upper end and in the operation of forming a last swings to one side only of the vertical plane in which the pivot for this frame is located. Referring to the accompanying mgz- The figure therein shown is a view in end elevation of a machine embodying my improveinents. v

Inasmuch as the machine shown is of the same construction as that disclosed in the Reed application referred to, except for the omission of certain parts and the addition of certain mechanism to cause the machine to drawembody my present invention, detailed showing and description of the machine appears to be unnecessary.

in explanation of the machine shown, it

may be stated that the machine comprises a frame 1 equipped at one end with cutting -mechanism comprising a roughing cutter 2 and finishing cutters one only of. which is shown at 3 which are rapidly rotated in the operation of the machine. At the other end of the frame is the usual pattern follower (not shown), the cutting mechanism and pattern follower thus being arranged in spaced relation.

The machine also comprises a swingframe a which is pivotally supported at opposite ends thereof, at its upper edge portion, tothe upper end of the frame 1, as by pivots one of which is represented at 5. This. swing frame has rotatably mounted thereon pattern and work supporting rotatable devices driven from the motor represented at 6. In the operation of turning a last, the rotating pattern and rotating work are forced against the pattern follower and the cutters, respectively, the follower and cutting mechanism, being fed in a direction lengthwise of the work and pattern. In the particular arrangement shown force exerted by gravity upon the swing-frame 4, tending to swing it to vertical position, is augmented by tensioning mechanism comprising pulleys 7 se ured to a shaft 8 adjacent the ends Jthereof,this shaft being journalled on the frame of the machine and equipped with a sprocket 9 which is driven by a sprocket chain 10 from sprocket 11 in turn driven by tlie motor 6, the pulleys 7, one only of which is shown, being rotated in clockwise direction in the drawing. The pulleys 7 are partially encircled by belts 12, the one at one, end only of the machine being shown, which extend over pulleys 13 journalled 'on the end portions of the frame of the ma chine, the lower ends of the belts carrying ll-C frame 1, the upper ends of these levers being pivotally connected at 18 with links 2U,

the forward ends of which are pivotally connected at 21 with the swing-fran'ie at at the ends thereof, the mechanism just described operating to equalize the force exerted against the swing-frame 4 and tending to move it to vertical depending position.

In accordance with the preferred illustrated embodiment of my invention 1 provide a spring, preferably one at each end of the machine, which is connected at one end with the lever 18 between the pivots 18 and 19 and at its other end with the swing-fran'ie 4:, this spring, or springs, exerting a force tending to swing the frame 4: toward depending vertical position and yieldingly resisting movement thereof out of said position. The spring device referred to comprises a spring 27 connected at one end with a portion, represented at 28, of the swingframe and extending below the pivot 21, and at its opposite end with the rod portion of a device adjustably connected with the lever 18 for varying the tension of the spring 27. The rod 29 is adapted to be positioned in any one of the rod-receiving-openings provided in the step portions of a bracket 30 secured to the lever 18, an adjusting nut 31 on the rod and bearing against the bracket 30 permitting of the desired tensioning on the spring. It will be understood that the adjustable spring device just described, may, and preferably is, provided at each end of the machine, so that the force exerted on the swing-frame at will be uniform at both ends thereof.

it will be understood from the foregoing description inasmuch as the members 18 and 20 constitute in effect a toggle the arms of which are connected together to one side of the toggle-joint by a spring under tension, that the spring exerts a force on the swing frame 1- forcing it toward vertical depending position.

The feature just referred to has been found to be of great advantage in a machine of the general type referred to, as it has been demonstrated that the pull exerted by the spring forcing the swing-frame to vertical depending position, is a constant pull without the vibration which is present in springs where they form a direct connection between the swing-frame 4t and the stationary frame of the machine, which vibrations produce chattering of the swing frame and consequently require that the ma chine be operated at relatively low speed. Where a machine is constructed with my invention embodied therein, it has been found that the action is such that the pattern even when presenting surfaces disposed at sharp angles to each other, closely hugs the follower at all times even when the machine is operated at relatively high speed, thereoy greatly increasing the capacity of the machine for producing lasts conforming with the pattern to the desired extent.

The adjustment of the spring devices on the levers 18 is provided so that the spring tension may be varied as desired, it being understood that it is desirable, to avoid wear on the pattern, that the force with which it: presses against the follower be as slight as possible and still permit of the proper hug-- ging of the pattern by the follower, those patterns presenting less abrupt corners or edge portions, requiring less spring tension.

While I have illustrated and described particular construction embodying my invention, I do not wish to be understood as intending to limit it thereto, as the same may be variously modified and altered without departing from the spirit of my invention. In this connection it may be stated that whereas my improved tensioning device is shown as incorporated in a machine involving other mechanism which operates to force the swing-frame 4t to vertical depending position, the invention is not limited to association with such mechanism, or in fact any mechanism in addition 'to the spring tensioning device, which latter may constitute, if desired, the only mechanism for swinging the swing-frame toward vertical position.

What I claim as new, and desire to secure by Letters Patent, is:

1. A copying lathe comprising, in combination, cutting mechanism and a pattern follower, a swing-frame for the pattern and work, a toggle pivotally connected at one arm with the stationary frame of the machine and at its other arm with said swing-- frame, and a spring yieldingly resisting movement of the arms of said toggle in one direction about the pivotal connection between said arms. 1

2. A copying lathe comprising, in combination, cutting mechanism and a pattern-fob lower, a swing-frame for the pattern and work, a toggle pivotally connected at one arm with the stationary frame of the ma chine and at its other arm with said swingframe, and a spring operatively engaging at one end with said swing-frame beyond the point at which said toggle connects with the latter and at its other end operatively engaged with the one of said arms of the tog gle at which the latter is pivoted to said stationary frame and yieldingly resisting movement of said arms in one direction about the pivotal connection between said arms.

3.'A copying lathe comprising, in combination, cutting mechanism and a pattern follower, a swing-frame for the pattern and work, a toggle pivotally connected at one arm with the stationary frame of the machine and at its other arm with said swingframe, and a spring operatively engaging at one end with said swing-frame beyond the point at which said toggle connects with the latter and at its other end engaging the one of said arms of the toggle at which the-latter is pivoted to said stationary frame, at a point yieldingly resisting movement of said arms in one direction about the pivotal connection between said arms. I

4. A copying lathe comprising, in combina-v tion, cutting mechanism and a pattern-follower, a swing-frame for the pattern and vwork supported adjacent its upper end, a

toggle pivotally connected at one arm with low the point at which beyond the joint of said toggle and p is pivoted to said stationary below the pivotal connection of the toggle with said frame, said spring operating to yieldingly resist movement of said arms in one direction about the pivotal connection between said arms.

HERMAN A. soHUL'rz said arms of the toggle at which the latter frame, at a point 

